Wavecaller's Invocation

At the beginning of each opponent's upkeep,
that player exiles the top card of their library.
At the beginning of your upkeep, return up to
X other target nonland permanents to their
owners' hands where X is the total converted
mana cost of all cards exiled with Wavecaller's
Invocation, then if X is 10 or more, return
Wavecaller's Invocation and all cards exiled
with it to their owners' hands.